1. Field of the Invention
The present invention relates to a fuel supply apparatus, and more particularly to a fuel supply apparatus for an internal combustion engine having first fuel injection means (in-cylinder injector) for injecting fuel into a cylinder and second fuel injection means (intake manifold injector) for injecting fuel into an intake manifold or an intake port.
2. Description of the Background Art
A fuel supply apparatus (fuel injection apparatus) provided with an intake manifold injector for injecting fuel into an intake port and an in-cylinder injector for injecting fuel into a cylinder, and controlling the intake manifold injector and the in-cylinder injector in accordance with an operation state to realize fuel injection by a combination of intake manifold injection and in-cylinder injection is known.
In such a fuel supply apparatus, it is necessary to secure a fuel injection pressure from the in-cylinder injector so as to spray the fuel directly into the cylinder. To this end, a configuration is disclosed where fuel is drawn from a fuel tank by a common low-pressure fuel pump and discharged to a high-pressure fuel supply system for the in-cylinder injection and to a low-pressure fuel supply system for the intake manifold injection, and while the fuel discharged from the low-pressure fuel pump is further increased in pressure by a high-pressure fuel pump to supply the pressurized fuel to the in-cylinder injector in the high-pressure fuel supply system, the fuel discharged from the low-pressure fuel pump is injected from the intake manifold injector in the low-pressure fuel supply system (for example, Japanese Patent Laying-Open No. 2001-336439).
The relevant document particularly discloses a technique of setting a ratio between the quantity of the fuel injected into the cylinder and the quantity of the fuel injected into the intake manifold taking account of the particulate state of the fuel injected into the cylinder in an internal combustion engine provided with such a fuel supply apparatus.